Transportation methods and apparatus



Oct. 12, 1937. A. F. WILLAT 2,095,730

TRANSPORTATION METHOD AND APPARATUS Filed April 23,. 1934 7 Sheets-Sheet 1 a 56 m K26 1a O gy 6/47 F155 if 1511 ATTORNEY.

Egg-F5515? Oct. 12, 1937. A. F. WILLAT 2,095,780

TRANSPORTATIQN METHOD AND APPARATUS I Filed April as, 1934 7' Sheets-Sheet 2 Z -47 m g 2/ Q -43 PIE. 5. r I

i FIE-1-5- i 1 AE/VOIlNoVE'WRZAT ATTORNEY FIE lE Oct. 12, 1937. I

A. F. WILLAT TRANSPORTATION METHOD AND APPARATUS Filed April 23, 1954 FIl'ilL FIEEEL IIIII 7 Sheets-Sheet 4 IN VENT OR.

Ka la {0% ATTORNEY.

Oct. 12, 1937. A.; F. WlLLAT 2,095,730

TRANSPORTATION METHOD AND APPARATUS Filed April 25, 1934 7 Sheeis-Sheet 5 l I q w: Al/2' ,vsArz'k m/v FAN v i Q I 8/ Sate/vow JP/en? F '15 INVENTOR.

ATTORNEY Oct. 12, 1937. A. F. W lLLAT- 2,095,780

TRANSPORTATION METHOD AND APPARATUS F'iled April 23, 19:4 7 Sheets-Sheet '1 I FIEJEL //////////A I "V 4 L/as' v ,7 YJ

FIELEEI- I FIEEL /o ATTORNEY.

Patented Oct. 12, 1937 UNITED STATES PATENT OFFICE TRANSPORTATION METHODS AND AP- PARATUS Application April 23, 1934, Serial No. 721,966

9 Claims.

This application is a continuation in part of my prior application Serial Number 622,295 filed July 13, 1932.

The invention is concerned with the utilization 5 of solid CO2 as a refrigerant. As is known, this material sublimes from a solid to a gas having a specific gravity of 1.53 times that of air.

The gas emanating from the solid CO: is, at the low temperature, very dry. In addition, it is an 10 active drying agent, an accepted explanation being that the following reaction occurs:

Carbonic acid is only known as a water solu- 1 tion of CO2. However, sucha solution has a lower vapor-tension than water and therefore evaporates more readily than water. When moisture is held in cell walls, as in a fibrous insulation, a water solution of CO: forms therein as a result 20 of osmosis, the solution thereafter evaporating more readily than water alone. This drying effect of cold C: gas is utilized in the present invention to preserve insulation for a cold chamber at a high degree of efilciency due to absence of water.

25 In connection with the use of cold, dry CO: gas as a dehydrator for the insulating material, this invention is concerned with a manner of discharge of gas into the insulation as well as the character of the gas discharged so that a very 30 efllcient insulation is secured by utilizing the gas to the utmost advantage. Hereinafter, therefore, certain details of construction and novel methods of construction will be disclosed since they lend themselves advantageously to the present 35 invention. It is tobe pointed out that in this invention the CO: gas is utilized to absorb heat- 45 the chamber but this gas is preferably not utilized thereafter to dry the insulation since this might lead to a wetting of the insulation. An air conditionin'g system for the chamber is also included to attain the end that the CO: content of the at- 50 mosphere in which are stored the products may be regulated and varied. Thus, the CO: content may be kept at a high value during the journey to prevent certain decay and, at the end of the journey, reduced so that men can enter without 55- masks.

The invention is also concerned with utilizing solid CO2 as an eflfective refrigerating medium for commercial storage spaces particularly on trucks, cars and vessels. In this connection I wish to point out that while it has been proposed 5 heretofore to utilize this material as a refrigerant, the control was such that emcient operation and uniform temperatures were not secured nor was the humidity of the cold chamber controlled. For example, Martin proposed, in his Patent 1,780,147, that the dry CO2 be liberated directly into the cold chamber to contact the products therein. Under this condition, if the products were not sealed in containers, their moisture content would be reduced. With products such as eggs which are graded and sold on a weight basis, any reduction in weight represents a financial loss to the shipper. Consequently, a system as proposed by Martin can not be generally used. In

accordance with this invention, the humidity condition's in the cold chamber are controlled and the water content thereof kept practically constant and at a-value consistent with the product or products in the cold chamber, as is the carbon dioxide content. 5

Solid carbon dioxide available commercially varies widely in its purity; this is to be expected since it is secured from such varied sources as natural wells, fermentation processes, chemical manufacture and stack gases. In addition it often contains lubricating oil and moisture. In accordance with this invention, the products in the cold chamber are kept out of contact with the sublimated gas so that any odors therein are not taken up by the products. In shipping such odor sensitive substances as butter, milk and cheese, the cold gas is not allowed to come into contact wlth'the products while its refrigerating and drying properties are utilized more or less fully.

In the commercial operation of a common re- 40 frigerator carrier, it is desirable that the products be precooled prior to shipment, since this reduces the load, due to respiration, on the refrigerator system of the vehicle or vessel. However, it frequently happens that the products are not precooled and'must be placed immediately in the refrigerator on the vehicle or vessel. In the case of 'erated chamber, illustrating details of not take up the sensible heat, the reaction heat generated, and lower the temperature as well, can not be successful. .The problem arises of adaptin: such a. system quickly to a very much lower rate once the latent heat and the reaction heat have been cared for and the temperature of the cold chamber reduced to theoperating temperature. That the change in operation must be made quickly to reduce the rate is a necessity, for otherwise the products may be frozen or at least subjected to an undesirably low temperature. A remote control is provided for securing this change.

The invention is also concerned with the control ofhumidity in the storage space. As has been pointed out, during the initial portion of the trip, cold is supplied at a high rate, particularly if the products have not been pre-cooled. During this period, the water content of the atmosphere is reduced by formation of ice on the cooling unit. If this is allowed to continue, the water content soon becomes too low and the atmosphere is so dry that dehydration occurs of products in the chamber. To avoid this, I propose to readjust the, mositure content, removing excess moisture or supplying moisture if there is any deficiency so that the humidity is that best suited to the products. The removal of water from air 'is quite continuous because condensation goes on most of the time when wanted, while but a short time is required to remove condensed water or frost.

In cold weather, the temperature of the cham- The invention includes numerous other objects and features which-will appear in the following detailed description of apparatuses and methods of my invention.

In the drawings: Figure 1 is a section through a refrigerated chamber including various features of my in vention.

Figure 2 is a section through the CO: carrying chamber of Figure 1.

Figure 3 is a. view, partly in section,-oi a fan shaft mounting in a refrigerator wall.

Figure 4 is a section through another refriganother cooling unit. p

Figures 5, 6, and 8 are diagrams of control systems and arrangements.

Figure 7 is a section of a conduit.

Figure 9 is a sectional side view, and Figure 10 a sectional plan view of another cooling unit and its arrangement.

Figures 11 and 12 are sections showing the construction of other units- Figures 13, 14, and 15 are diagrammatic represefitations of control systems.

Figure 16 is a sectional view andFigure 17 an elevational showing of insulation construction,

Figure 18 isa CO2 gas appliance.

Figure 19 is a section of another unit.

Figures 20, 21, and 22 are conduit constructions.

Figure 23 is a section in side elevation, and

Figure 24 a section in plan to illustrate gas circulation.

In Figure 1 I have shown a refrigerator em- 5 bodying features of my invention. The chamber for the products to be maintained cold is indicated by 2|. This chamber can be of any suitable construction but I prefer that presently describedin detail in connection with Figures 16 10 and 17. The chamber can be mounted on a truck chassis, placed in a steamer hold, or it can be a refrigerator car, or whatever other character of cold chamber is desired.

To supply cold to the chamber, a container 22 15 is provided for the solid CO2. This container is preferably heavily insulated so that substantially all heat carried into the solid CO: packed in the container is carried. in by the sublimed CO2 gas which passes through sheet metal conduit 23. 20 The conduit 23 extends along the bottom of the container and up one side so that cold heavy gas can enter through port 24 and pass along the conduit in only thermal contact with the atmosphere of the chamber, rising as it takes up heat, 25 to return through port 26 to contact with the solid CO: in the container. A hand valve 2| is provided to close on port 24 or to regulate the maintained. The valve member 28 is carried by a member which can be a strip of bimetal, as. in Figure 11 of my prior application, or it can merely be a support, the position of which is determined by temperature responsive and regulatable means.

Since the invention'is primarily concerned with large scale commercial refrigeration wherein the weight of products carried in chamber 2| is measwed in tons, I provide means for circulating the atmosphere of the chamber so that a uniform temperature can .be maintained even in remote P rtions of the chamber. Sheet metal member is provided adiacent the conduit 23 and forms a trough about the conduit. This trough is continued to adjacent the top ofithe chamber by another sheet metal member 32. At the top of the chamber, the trough flares and .is so arranged that the cold atmosphere is directed to all portions of the chamber. The product side of the drip pan and trough is covered with a layer 30 of heat insulating material so that moisture does not condense thereon and thereafter drip onto .the products beneath.

To assist in forcing the cold atmosphere about, I provide a fan 33 on a shaft 34 for forcing the atmosphere over bottom 36 of the conduit and through the trough. The shaft 34 is preferably extended through the wall of the chamber to a motor 31. As appears in Figure 3, a tube 38 ot a poor heat conductor as bakelite is held by collars 33 against the walls, the shaft extending through the tube and being sealed by several felt washers 4|. Several fans can be used if desired.

The bottom 36 of the conduit is preferably fluted or corrugated as appears at 42 in Figure 2.

This increases the metal surface and permits of,

cluding the side walls and bottom, can be so constructed, as-I have indicated in Figure 7, or fins can be used However, the fiuted or corrugated construction is a. simple one.

The container 22 is shown as suspended by brackets .43 from the ceiling of the chamber. It can also be supported from the side walls or from the floor, as in Figure 4. But no matter how it is supported, an air space is preferably left about the container so that any efiect of the extremely cold CO2 stored in the container is utilized to cool the chamber .rather than to cool its walls directly,

The contents of the container 22 are replenished through door 44 which can be securely latched in place by latch 46 to keep container 22 gas tight. To reduce heat losses, 9. door 41 is provided in chamber 2| so that the container can be re-iced without entering the chamber through the main entrance way, door 41 being adjacent door 44, I

To permit of container 22 being completely filled, ports 24 and 26 are formed respectively in a side wall and in the top so that the CO: ice can not clog them, spacing rails 48 being included in the container. By having the ports formed in this manner, a longer gas travel path is secured, and the flow of gas is directed onto the solid CO2 in the container 22, while the rails prevent clogging the ports.

In operation, the speed of the motor is controlled to vary the rate of cooling of the chamber as well as to eifect a control of the chamber humidity. When the motor runs slowly, the moisture in the room condenses and possibly freezes on bottom 36. This reduces the total water content of the chamber atmosphere. To assist in this, vane 48 is provided in the trough, the vane being offset but balanced by weight 49 about shaft 5|. When the fan runs slowly, the vane is in the full line position in Figure 1. In this position, the atmosphere passes through the trough slowly and is cooled by contact with the conduit 23. v

When the motor is run at a higher speed, the force of the fan discharge striking the turned end 52 of the vane moves the vane to the dotted line position in which the atmosphere is directed against the bottom of the conduit 23. This results in melting of the ice on the bottom of the conduit. The water thus formed drips down onto member 3| and collects in a sump formed by lip 53 on member 3|. A pipe 54 and valve 55 serve to control the removal and disposal of water thus collected.

If the humidity of'the room is too high, as

shown bycomparison of a dry and wet bulb thermometer, the collected water can be drained oil. If, on the other hand, it is desired that a certain humidity be maintained in the chambenavolume of water can be atomized inthe chamber, the

volume atomized depending on the control anddegree of humidity desired. While a hand atomizer can be used, I- have shown an automatic air operated device 56 in Figure 1 which will atomize water and discharge it at a known rate, atone or more points in the chamber, as desired.

While the foregoing operation can be obtained by a supervising operator, I prefer to have it automatic. In Figure I have shown an automatic operating system which includes an operating device 6| for valve member 28, the spray devices 56, valve- 55 and motor 31. These are under the control of a clock 51, a hygrostat 58 and a thermostat 59. Whenever the temperature rises also controls heater 19 in the chamber 2|.

above a predetermined value to which the thermostat is adjusted the operating device 6| for valve member 26 is actuated whereby the valve member is moved and the motor is operated at full speed. While full speed operation of the motor results in de-icing of the bottom of the conduit, valve 55 is opened and closed by a solenoid 62 controlled by clock 51 and hygrostat 55. These also control the atomizer or spray device 56. Now moisture is taken out of the atmosphere normally very slowly and only periodic operation of valve 55 and spray device 56 is desirable. The clock 51 (see Figures 13 and 14 also) therefore is superimposed on the hygrostat and, if. the hygrostat determines that a given operation is necessary, the operation occurs only at the next critical time as determined by the clock, usually once each hour or every two hours. The clock can either permit operation for a predetermined time or else merely initiate a called for operation. The hygrostat can speed up the motor if necessary even if the atmosphere is cold enough since but Y A simpler form of apparatus includes spray device 56 arranged to spray into the fan discharge through the trough so that moisture is quickly carried to all parts of the chamber. In this case, valve 55 is omitted, pipe 54 draining any water collected. When the fan runs at high speed, its

air stream defrosts the plate 86 and carries the water vapor thereafter discharged into it from device 56 ,to all parts of the chamber, device 56 being in the high speed fan circuit. It is only necessary in this form to have the fan controlled by a device 68 which can be operated thermostatically and the spray device controlled by the hygrostat which can also run the fan at high speed as in Figure 8.

. The air fan alone can be used to control humidity and the vane need not be used. However, the vane enables a higher air circulation rate to be attained without defrosting.

Another system of operation is to let the fan run at such a speed at all times that moisture collects onbottom 36 and drips into the pan or trough 3|. Valve 55 is then controlled by the hygrostat 58 so that as long as the atmosphere is dry, the water remains in the trough, but when the atmosphere'is too wet, the valve opens and the water drains off. If the atmosphere gets too dry, the hygrostat not only keeps the valve closed but operates spray device 56 as well.

In Figure 13I have shown one control system in some detail as applied to remote control on panel board 1|. The operating elements 12 and 13 of the wet bulb 58 and the dry bulb 59, the

active elements of which are in the chamber 2|,

are shown associated with contacts 14 and knobbed disc 15 of the clock device 51. These respectively control the CO2 fan 16 and the spray device 56 and the air fan 11. The circu t to the CO2 fan is controlled by knob switch 18 which With this arrangement the CO2 fanand the heater cannot be operated at the same time although the air and heater can be. In shipping into ,cold climates it happens that the atmospheric temperature is' lower than that of chamber 2| so that it is desirable to heat-the chamber and protect the products therein against too much cold as wellastoomuchheat.

A resistance type thermometer 00, operated by battery I and including knob switch 02 and resistances 03 disposed about the cold chamber is included. Switches 34 and 80 provide for control of the battery and its recharging from power lines 80.

Rheostats 31 are mounted on the back of the board. An alarm signal 08 is also included to be operated by push button 89 in the chamber if anyone should be locked therein by accident.

conditions to a satisfactory degree by the coldleakage through container 22. In Figure 4, chamber, 2I includes container 22, supported therein, with a conduit IOI extending from one high level port I02 to another high level port I03. A fan I00 driven by a motor I06 is placed in the conduit and forces the C0: gas about the circuit which includes the conduit and the container 22 having solid CO2 therein below ports I02 and I03. It is to be noted that the ports direct the gas down and about the refrigerant so that the gas is cooled upon contact with the CO2. Usually bare solid C02 is used in precooling and ice wrapped in paper for ordinary refrigeration. Suitable vanes I can also be used to direct the circulated gas over the ice, or other circulation directing means. In Figures 23 and 24 return duct Ill, later described in connection with Figures 9 and 10, is shown as including its outlet at the bottom of the chamber I I I which is much the same as chamber 22. Air and gas forced through duct I I4 is released beneath'apertured plate II 0 spaced from the bottom of the chamber. This plate can be a sheet of metal suitably apertured or any other suitable support means as wooden slots. Irrespective of materials, however, the plate is usually'provided with a vane I I5 so that gas is forced along the bottom of the chamber, between the chamber and the plate I I0 to prevent short circuiting to the end that gases entering outlet duct II6 are very cold because they have been forced under and in and about the solid CO2.

When the sensible heat of the load has been taken up and the load cooled to between 32 and 40 F.,'the exothermic reactions proceed at a very low rate,,practically zero. The fan I04 then need be rotated only when it is necessary to preserve the desired temperature, say 32 F. or some other definite temperature.

Since the inlet and outlet ports are at a high level and also at the same level, control is simpllfled. Gold is secured by forced circulation of the gas through the conduit and since this can be varied widely, the rate of cooling extends between wide limits. The essential to simplified control is the fact that the inlet and outlet ports are at the same level since this cuts ofi any thermal circulation by thermo-syphon eifects. The inlet and outlet ports can be at the same level aoesnso along the sides of the container 22 or at the tom so long as they are at the same level;

To cut down any localized circulatiiiii as a e'- suit of thermo-s'yphon effects, the conduitl 0| can be sub-divided, as in Figures 20, 21, and 22 hereof," and as in Figures 13 and 14 of mycopending ap'- collars adiacentto the refrigerating container where the conduits enter and leave are of material assistance.

In Figures 9 and 10, I have shown additionally two solid CO2 containers III and H2 on each side of the chamber and adjacent loading door 3 for the chamber 2|. These containers are connected by two parallel fiues H4 and H3 through which gas is forced by fan I" in flue II6. A trough I I8 is extended about the conduits and a fan II9, driven by a motor I2I carried on the door, serves to circulate the atmosphere of the chamber about the fiues or ducts. Since the gas ports are at the same high level and are above the solid C02, when the fan is not operating the gas does not flow even by natural circulation and the only cooling effect is that which leaks out of the insulated CO2 container.

In the case of the apparatus in Figure 4 and Figures 9 and 10, the control can be after the manner in Figures 1, 5, and 6, and 13, except that the control for valve member 28 can be omitted as that element is not employed usually. In addition, the air and gas ducts, fines and troughs can be fluted, corrugated or finned after the manner of Figures 2, 7, 20, 21, and 22 and the trough II8 can include the vane 49.

While the structures shown in Figures 4, 9, and 10 permit of controlled circulation from zero to a very high rate, in some-instances it is desirable to use another circuiationsystem. In Figure 19 I have shown a structure wherein solid CO: container I3I includes a conduit I32 within which is a fan I33. This fan, when operating, forces gases down and into the solid CO2, the opposite of the normal path, so that swing valve I34 is moved from oil? of seat I36. When the fan is not operating, the valve is seated and cold CO2 gas can not circulate through the conduit since the valve prevents this. Conduit I32 can be made as in Figures 7, 20, 21, and 22, and valve I 34 included therein. I

In Figures 11 and 12 I have shown another satisfactory device in which container 22 is supported in chamber 2 I. This chamber includes a metal duct I35, one side of the duct forming the base on which rests the solid CO2. In Figure 11, a fan I30 forces airthrough the-duct to discharge cold air into the chamber while in Figure 12 a flexible belt I31 passes through the duct and over pulleys I30. The belt includes a plurality of slats I33 which, upon driving of the pulleys by a motor, are passed through the duct. The slats wipe the sides, top and bottom of the duct and keep it free of ice as well as circulating air through the ductso that the air is cooled by contact with the duct. If the air passed through the duct is cooled too much, a lower rate of air circulation can be used, as well as insulation placed'between the solid CO:

- while on a trip because the door might leak, I include a heat insulating collar I40, as shown in Figure 11, between the container 22 and chamber 2 I. when the chamber is not being iced, the collar is filled with a mass of insulating material in a pillow or pad I50 made to fit the collar and filled with insulation. In Figure 4, the door 44 has been omitted and several pads I50 employed instead.

The control of the described units can be in accordance with any of the several operation schemes disclosed and with combinations thereof.

In Figures 14 and 15 I have shown other control systems, that of Figure 14 being particularly adapted to the structure of Figures 9 and 10. In this system, wet bulb 58 includes two contacts I80 and I 8|. When the atmosphere is too humid, contact I8I is engaged and with clock device 51 in such a position that contacts 14 are open, a circuit is completed to relay I82 so that arm I83 engages contact I84 to pass current through resistance I86 and through only a portion of resistance I81. This resistance is in series with the motor of CO2 fan 16 which is connected across power line 86 so that the C02 fan always operates. The relation of resistance I88 and I81 to the motor is such that the motor runs at a higher speed when only resistance I81 is cut in. When resistance I86 cuts in on a. portion of resistance I81 the motor operates at a lower speed. When resistance I86 is cut in, current also passes to the air drying fan 113, the relay and the fan being in series at this time. This fan is also in series with a resistance I88 and line 85. The resistance I88 is such that when the circuit through contact I8I is open, the fan runs slowly,if at all, while it speeds up to some extent when the circuit through contact I8I is closed.

With the C03 fan running slowly, the gas circulates through the ducts I I4 and I I8 and moisture condenses thereon, thus lowering the water con-..

tent as the moisture condenses and possibly freezes. when the clock closes contact 14, the relay I82 is shorted out whereby the fan 113 runs still faster to melt some of 'the frost. If the air istoo dry, a circuit through contact I 80 is immediately completed andspray-device 56 operates. Depending upon the temperature, fan 11A may or may not be operating, this being controlled through dry bulb 58 and its contact I80. The spray device may discharge into the air stream from fan 11A as well as 113.

The temperature inthe chamber is controlled .by the dry bulb 58 which, with contact I80, cuts fan 18 and fan 11A in at full speed if the temperature is too high, contact I80 shorting out resistance I81 on fan 18. When the temperature is too low-if it is necessary to protect the products against too low a temperature as when the temup for this is shown in Figure 15. Wet bulb 58v includes a contact 200 and drybulb 58 a contact 20I. When the temperature is too high, the dry bulb engages contact 2M and runs the CO2 fan and the air fan rapidly so that cooling occurs.

- When the contact 20I is not engaged, the series resistances 202, 203, and 204 prevent the CO2 fan from operating unless the wet bulb engages its contact 200. .Inthis case, resistance 204 is cut out and the air fan and CO: fan both operate, the CO: fan slowly and the air fan more rapidly, though not at full speed, so that moisture condenses on the cold pipes. This system can be used in conjunction with suitable portions of the other systems. Thus the heater 18 and the spray device 58 can be included.

The excess gas present in the conduit system is dry and free from any of the atmosphere of the chamber cooled. This gas is used to advantage to insulate and keep dry the walls. of the CO2 container as well as the chamber 2i. To permit gas to be discharged into a space or collected from a one end and includes numerous small apertures I42. Collars I43 screwed onto the tube hold it in position, gaskets being used if desired. The gas pipe I44 is connected to the tube by nut I46. This unit is attached to the chamber 2| at any convenient place usually in the ceiling as in Figure l. r

'A high level outlet is also usually employed from the insulation to ensure a low rate of CO2 circulation and thorough permeation of the insulation. Relatively deadCOz gas is desired in the insulation rather than a fast moving stream.

If desired, C02 gas can. be admitted into the chamber atmosphere though this is not usual. In fact the presence of CO: in the chamber due to respiration may be considerable and I therefore provided a fresh, air inlet N611 and air outlet I41 controlled by suitable valves I 48-operable from a remote point to admit new air, possibly conditioned, and exhaust the atmosphere in the chamber, a suitable ventilating system being thus provided. Since the CO: content on respiration has been found to be as high as 40%, attention is given to this factor.

The chamber 21 (Figures 16 and 1'1) is preferably formed by building a frame work of. members I5I spaced from members I52 by spacers I53, the whole being suitably braced. An outer covering is fastened to members I5I. This covering is preferably air tight, two, three ply composite boards I54 with a layer of air and moisture tight roofing paper I55 between and fastened to members I5I, being satisfactory. The insulation is next placed. While this can be done in various ways, I prefer to deposit a fibrous insulation as cotton fibers or kapok with air since this gives a uniform and satisfactory wall. 'To do this, members I51 are secured between members I52 and a length of porous cloth I58 as burlap is nailed in place. The insulation is then fed into "place in an air stream from a blower, the material being fed into a centrifugal-blower or apparatus such as that shown in Patents 874,752, 1,550,037, and 1,789,096 being used. A top covering is placed temporarily and the insulation blown in,

the burlap letting out the air. When the burlap bulges and seems uniform, the false cover is removed and a strong cord I58 is wound back and forth toform a cover for one layer and a support for the next. When the wall is complete, two layers of three ply board I 6i with roofing paper I62 between, are nailed on over the burlap. The same procedure is followed for each wall, the

top, bottom, and doors, except that string is not needed on floor and ceiling.

A satisfactory way to fasten the string is to run the string through an automatic hand stapling machine of a type commercially available,

supplemental ring guides for the string being provided. The stapling device is 'known as a.

Bostitch stapler.

I claim:

1. A method of reducing the quantity of solid CO: required to refrigerate products that generate heat by ripening or decay reactions when stored in a refrigerating container, said method comprising circulating gaseous CO: in a closed circuit from a body of solid CO2, circulating air in said container over a portion 91' said circuit at a rate sufficient to cool said products to a'predetermined temperature and absorbheat generated by said products as well as freeze said products upon continuation of said circulation of air, and then circulating air at a rate insufficient to freeze said products but sufficient to maintain said products at said predetermined temperature.

2. A method of reducing the quantity of solid C02 required to refrigerate products that gencrate heat by ripening or decay reactions when stored in arefrigerating container, said method comprising circulating gaseous CO in a closed circuit from a body of solid C0: and, circulating air in said container over a portion of said circuit, said circulaton of gas and air being at a rate sufficient to cool said products to a predeter- I mined temperature and absorb heat generated by said products as well as freeze said products upon continuation of said circulation, and then circulating gas and air at a rate insuflicient to freeze said products but sufilbient to maintain said products at said predetermined temperature.

3. A method of refrigerating products in a refrigerating container with a body of solid CO2 comprising circulating CO2 gas in a closed circuit from said body, circulating air in said container to abstract heat from said products and transmit said abstracted heat to said body of C0: through said circuit at a rate suflicient to freeze said products until a predetermined temperature is attained, and then circulating air in said container to abstract heat and transmit said abstracted heat to said body of CO2 through said circuit at a rate only suificient to maintain substantially said temperature.

4. In combination, a refrigerating chamber in cluding therein a first chamber for solid CO2, a second chamber for solid C02, afirst and a second conduit extended between said chambers and joining said chambers to provide a circulatory system, and means for forcing air in said chamv ber oversaid conduits.

the temperature in said chamber is 5. In combination, a refrigerating chamber including therein a first chamber for solid 00:, a second chamber for solid C02, a first and a second conduit extended between said chambers and joining said chambers to provide a circulatory system, said conduits being connected to said chamber above the solid CO: level in said chambers, and means for forcing air in said chamber over said conduits.

6. In combination, a refrigerating chamber including therein a first chamber for solid CO2, a second chamber for solid CO2, a first and a second conduit extended between said chambers and joining said chambers to provide a circulatory system, means for forcing C0: through said system, and means for forcing air in said chamber over said conduits.

7. In combination, a refrigerating chamber including therein a first chamber for solid CO2, a second chamber for solid CO2. a first and a second conduit extended between said chambers and joining said chambers to provide a circulatory system, said conduits being connected to said chambers above the solid CO: level in said chambers, means for forcing 00: through said system, and means for forcing air in said chamber over said conduits.

8. ,In combination, a refrigerating chamber including therein a first chamber for solid CO2, a second chamber for solid C02, 9. first and a second conduit extended between said chambers and joining said chambers to provide a circulatory system, means for forcing 00a through said system, means for forcing air in said chamber over said conduits, and means controlling operation of vsaid forcing means for operating both said means when temperature in said chamber is joining said chambers to provide a circulatory system, said conduits being connected to said chambers above the sblid'CO: level in said chambers, means for forcing 00: through said system, means for forcing air in said chamber over said .conduits, and means controlling operation of said forcing means for operating both said means when temperature in said chamber is above a predetermined temperature and for operating only a selected one of said forcing means when below said predetermined temperature.

ARNOLD F. WILLAT. 

